Keltner discovered another of its purposes: When we witness suffering, our vagus nerve makes us care. If you see a photo of a man wincing in pain, or a child weeping for her dying grandmother, your vagus nerve will fire. Keltner also found that people with especially strong vagus nerves—he calls them vagal superstars—are more likely to cooperate with others and to have strong friendships. They’re more likely (like Rolf) to intervene when they see someone being bullied, or to give up recess to tutor a classmate who’s struggling with math.
